[Outbreak of intestinal infectious diseases due to contamination of two-time pressure water supply with sewage].

Two outbreaks of intestinal infectious disease occurred due to contaminations of Two-time pressure water supply at Hai-zhou and Tai-ping districts in 1985 and 1986. There were 659 cases, the incidence rate was 55%. The cause of contamination was that the underground water storage tanks were contaminated by domestic sewage, which back-flowed into the tanks through an overflow pipe, connecting the tank with observation well of the sewage system.